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<TITLE>How to choose optimal archiving settings</TITLE>
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<P class="title"><A NAME="HELPArcOptimal"></A>How to choose optimal
archiving settings<hr></P>

<P>When creating a new archive, you are presented with several compression
related parameters on <a href="HELPGetArcGeneral.htm">General options</a>
page of "Archive name and parameters" dialog. Firstly you need to select
the archive format, which can be <a href="HELPRARVersusZIP.htm">RAR</a>
or <a href="HELPRARVersusZIP.htm">ZIP</a>. ZIP is preferable if you are not
sure that receiver of your archive has WinRAR or other software able to
unpack RAR archives. Otherwise it is recommended to choose RAR,
which supports more functions and higher compression.</p>

<P>Regardless of the archive format the next step is selection of
compression method. You can choose among "Store", "Fastest", "Fast",
"Normal", "Good" and "Best" methods. "Best" provides highest,
but slowest compression, "Fastest" compresses poorly, but is very fast,
"Store" adds files to archive with maximum possible speed, but without
any compression. "Fastest" might be more suitable for daily backups,
"Best" for Internet distribution, "Normal" for everyday use like
compressing email attachments.</P>

<p>If you selected the ZIP archive format, your preparations are finished
at this stage. In case of RAR, there are two more important options
affecting compression: dictionary size and solid archiving mode.</p>

<p>Compression dictionary is the memory area used by compression algorithm
to find and compress repeated data patterns. Larger dictionary frequently
improves compression of big files, especially in solid mode,
but it also leads to slower compression and higher memory requirements.
Normally we recommend to use 32 MB for RAR archive format. You can read more
about the dictionary size <a href="HELPGetArcGeneral.htm#DictSize">here</a>.</p>

<p>"Create solid archive" option compresses files as single contiguous 
data stream resulting in higher compression ratio when processing many
small similar files. But it also reduces speed of further archive 
modifications and increases amount of data loss in case of archive damage.
This mode is explained in details <A HREF="HELPArcSolid.htm">Solid
archives</A> topic.</P>

<P>These are all the main settings, which affect compression ratio
and speed. Actually, you do not need to set them before every archiving.
Simply select your favorite default values once in the default 
<A HREF="HELPProfiles.htm">compression profile</A>, which can be created
in <A HREF="HELPCompressionSettings.htm">Compression settings</A> dialog.</P>

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